All the Outback Power products that perform battery charging have and integrated temperature compensation function that require the remote temperature sensor (RTS). If your Outback Power system has multiple charge controllers or inverters connected to one HUB4 or HUB10, you will only need one temperature sensor. We recommend using the Outback RTS whenever the temperature in the batteries is subject to variations during the year. The RTS will measure the temperature at the batteries and provide a more accurate charging. The RTS is compatible with Outback Flexmax chargers and inverters.